This invention relates to printed circuit boards, and more specifically relates to a novel structure of a printed circuit board and novel method for its fabrication.
Printed circuit boards are well known in the art. Conventional printed circuit boards consist of flat laminates, for example, of a phenolic which has a conductive pattern formed thereon. The conductive pattern usually consists of a copper foil which is adhesively secured to the surface of the phenolic board, with sections of the foil removed as by etching in a photolithographic process to define the desired conductive pattern. The board is also machined, drilled or punched to provide the necessary openings through the board to provide for mounting and for passage of conductors from one side of the board to the other. The presently used conventional process is expensive since it requires numerous steps which are separately performed on individual boards.
Molded circuit boards are known wherein a thermosetting or thermoplastic material is molded by any traditional molding technique. A copper foil is then adhesively secured to the top of the molded body and is patterned to define the desired conductive traces. It is known that during the molding, desired openings or other surface features can be directly formed on the molded circuit board.
Presently existing molding systems, like the conventional circuit board employing a phenolic base, require numerous manufacturing steps and numerous steps in the application of the circuit patterns, although some expense is saved by the ability to form openings in the molded body during the molding process. Molded circuit boards, however, are still expensive and have experienced poor bonding between the conductive patterns and the molded board.